Air freight handling system



June 26, G. MAXON, JR 2,379,094

AIR FREIGHT HANDLING SYSTEM 7 Filed May 1, 1943 '7 Sheets-Sheet l F/Fnwy Mwmnj". I emj June 26, 1945. G. MAXON. JR

AIR FREIGHTHANDLING SYSTEM Filed May 1, 1943 '7 Sheets-Sheet 2 wwkw [HA-WW Max:727 J7".

June 26, 1945. G. MAXON, JR 2,379,094 A AIR FREIGHT HANDLING SYSTEM Filed May 1, 1943 '7 sheets sheet 3 June 26, 1945. xoN, JR

AIR FREIGHT HANDLING SYSTEM '7 SheetsSheet 4 Filed May 1, 1943 "plane Fuse/aye 07 M72602? J7". W

June 26, 1945. G. MAXON. JR 2,379,094

AIR FREIGHT HANDLING SYSTEM Filed May 1, 1945 '[Sheets-Sheet 5 June 26, 1945. MAXON, JR 2,379,094

AIR FREIGHT HANDLING SYSTEM Filed May 1, 1945 '7 Sheets-Sheet 6 1&12.

June 26, 1945.

cs. MAXON, JR

AIR FREIGHT HANDLING SYSTEM Filed May 1, 1943 '7 Sheets-Sheet '7 jwww F/mwy Mum? J 1 {A v W15 7 Patented June 26, 1945 UNITED STATES PATENT OFFICE AIR FREIGHT HANDLING SYSTEM Glenway Maxon, J r., Milwaukee, Wis. I I

Application May 1, 1943, Serial No. 485,278

17 Claims.

This invention relates to the handling of air freight, and has as its object to provide an expedient system of loading and unloadin airplanes.

While airplanes designed exclusively for the transportation of cargo and freight are still in the development stage, sufficient experience has been gained in the carriage of air cargo to bring into bold relief the need for an efficient and facile manner of handling the cargo and freight during the loading and unloading of the airplanes.

The weight and size of the individual pieces of cargo contemplated to be carried, of itself makes such past systems as employed in the dispatch of air express impractical and out of the question. In the handling of the relatively light packages and baggage carried by air express, it was a simple matter to taxi the airplane close to the depot or central loading station and truck the packages or baggage out to the airplane where they were lifted by hand from the truck into the airplane.

In military operations where heavier cargo has been and is being transported by air the total absence of effective machinery for handling the cargo led to the use of ramps and more or less makeshift inclines leading from the ground to the sill of the airplane door. Vehicles and gun carriages could then be driven or pushed up and down these ramps to effect loading and unloading, but obviously there is no expediency in this method of handling cargo. The full force of its deficiency can be easily appreciated from the fact that the height from the door sill to the ground varies widely with the different types of airplanes in use today;

In the limited experience of some of the commercial air lines this variation in the doorsill to ground height resulted in serious delays, trip cancellations and inability to operate on schedule.

Standardization of the doorsill to ground height, if possible, would overcome this difficulty but enforced adherence to such limitations undoubtedly would hamper the future design of the cargo carrying airplane. It is therefore safe to assume that for a considerable future period variation in doorsill to ground heights will be encountered. At present these heights vary from three feet siX inches (3' 6") for some types of airplanes. to nine feet eight inches (9 8") for other typesa difference of six feet two inches (6' 2").

Another important factor which has a serious bearing upon any means employed for the hanthe cargo has its specific place in the cargo compartment determined by the weight and size of the piece so that the center of gravity of the entireload will be properly located in the airplane. The piece must, therefore, be brought into the airplane in a definite order.

Hence, if time consumption in the loading and unloading of airplanes, especially loading, is to be reduced, it is essential that provision be had for spreading out the intended cargo at a point close to ths actual loading location. If the airplanes could be taxied close to a large central depot or loading station this might be easily effected, but because of the relative large size of cargo carrying airplanes it is inexpedient to say the least to attempt such concentration of the airplanes at a central loading depot.

Moreover, it may well be that the central loading depot would be most advantageously located at a point to which it would be impossible to taxi airplanes. Such a condition would be met where a railroad track lies between the loading station or depot and the airfield.

It is therefore an object of this invention to provide a cargo or freight handling system adapted for the expeditious loading and unloading of airplanes scattered over a relatively wide area or located at points quite remote from the central loading depot.

Another object of this invention is to provide a cargo and freight handling system having provision for accommodating airplanes of different types with different doorsill to ground heights.

In a broad general way, these objectives are attained by the present invention through the provision of portable load carrying platforms adapted to be removably carried on the elevatable frame of a hoist truck or other suitable prime mover and by which these platforms may be transported from the loading platform or dock of a central receiving and dispatching depot to portable slips which may be towed out onto the field by the prime mover to positions close to the locations at which the airplanes are to be loaded or unloaded.

Hence, through the use of a sufficient number of portable slips and removable load carrying platforms deposited thereon and with these slips adjacent to the airplane being loaded or unloaded a convenient working area is provided on which the cargo can be arranged to facilitate proper sequential loading. The loaded platforms can then be picked up by the elevatable frame of the prime mover and elevated to the height of the airplane doorsill for transfer of the cargo or freight thereon into the airplane.

In addition to the broad objectives stated hereinbefore, this invention has as another of its objects the provision of a novel U-shaped portable slip into which a truck or other prime mover may be backed to deposit a load carrying platform removably carried by the truck or to lift such a platform off the slip, the slip being adapted to be towed by the prime mover to any desired location.

Another specific object of this invention resi es in the provision of portable slips having retr tible wheels so mounted that elevation of the load supporting frame of the truck may be utilized to bring the retractible wheels into operative ground engaging positions enabling the slips to be towed.

Still another object of this invention resides in a simple latch mechanism automatically operable to releasably secure the wheels of the portable slips in their operative ground engaging positions and in the provision of a simple manually controlled release for the latch mechanism.

With the above and other objects in view, which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate one complete example of the physical embodiment of the invention constructed in accordance with the best mode so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a perspective view illustrating the general organization ofthe system embodying this invention;

Figure 2 is an enlarged perspective view illustrating part of the central freight depot, two of the portable slips, and the prime mover;

Figure 3 is a side view of the prime mover and one of the portable slips coupled together preparatory to raising the slip off the ground;

Figure 4 is a view similar to Figure 3 illustrating the manner in which ascent of the elevatable load carrying frame of the prime mover is used to lift the slip and bring its wheels into operative positions;

Figure 5 is a view similar to Figures 2 and 3 but showing the elevatable frame of the prime mover lowered preparatory to travel;

Figure 6 is a plan view of the prime mover and the slip hitched thereto;

Figure '7 is a side view of the prime mover with its load elevated and illustrating the manner in which cargo and freight may be moved from the load carrying platform into the airplane fuselage and vice versa;

Figure 8 is a plan view of the structure shown in Figure '7;

Figure 9 is a detail cross sectional view through one of the permanent slips at the central freight depot illustrating the manner in which the portable load carrying platforms are supported therein;

Figure 10 is a view in side elevation of one of the portable slips and illustrating the prime mover backed into it;

Figure 11 is a rear end view of the truck or prime mover in position in a portable slip with the slip indicated in light lines;

Figure 12 is a side view of a slip of somewhat different construction;

Figure 13 is a partial top plan view thereof;

Figure 14 is a detail cross sectional view taken on the plane of the line -44 in Figure 12;

Figure 15 is a perspective view of the latch controlling mechanism embodied in the slip shown in Figure 12;

Figure 16 is a diagrammatic view illustrating the manner in which the slip may be manually raised onto its wheels; and

Figure 17 is a view similar to Figure l4 illustrating still another way of centering the portable platforms on the slips and the prime mover.

Referring now particularly to the accompanying drawings, and with reference specifically to Figure 1, it will be seen that the cargo and freight handling system of this invention consists broadly of a more or less permanent central freight depot 5 having a platform I provided with a number of slips 1.

The location of the depot I is dictated by factors based largely upon its accessibility to trucks and railroads, if possible. Hence, it may be some distance from the airport. In any event, the depot 5 would be located a substantial distance from the runways of the airport and also from those areas of the airport to which it is convenient to taxi the planes for loading and unloading.

Figure 1 illustrates a plane 8 in position to be loaded or unloaded and to and from which freight is carried by a prime mover 9. The prime mover is preferably an automobile truck having an elevatable load carrying frame It adapted to be raised and lowered by hoist mechanism of the type generally similar to that illustrated in Patent No. 2,219,525, issued to Glenway Maxon, Jr., October 29, 1940.

The prime mover carries its loads on portable load carrying platforms ll detachably mounted on the elevatable frame l9 and adapted to be deposited in the slips 1 or on portable slips I2.

The portable slips l2, of which an adequate number is supplied, are adapted to be towed out onto the field into close proximity to the point or points at which the actual loading and unloading operation takes place. Thus, during loading and as suggested in Figure 1, the prime mover in one trip out from the central depot 5 may carry a loaded platform and tow one of the portable slips out on location. Arriving on location the slip is deposited in position and then the truck backs into the slip with its load elevated and when in position therein deposits its loaded platform on the slip by lowering of the elevatable frame ll.

When all of the cargo or freight to be loaded is brought out on location in this manner, it is properly arranged on the platforms to insure the correct order of loading and then the prime mover is backed into the portable slip supporting platform on which the first-to-be-loaded cargo or freight is piled, picks up the loaded platform and backs close to the plane so that when its load is elevated as shown in Figure '7 to the height of the sill of the doorway I! in the fuselage of the airplane, the cargo or freight may be easily and quickly transferred from the loaded platform into the fuselage. This sequence is, of course, repeated until the entire load is stowed in the airplane. During unloading, the reverse procedure is followed.

To facilitate the transfer of the cargo and freight from the elevated platform to the airplane and vice versa a roller ramp H is pro .lectibly carried by the elevatable frame of the prime mover as shown in Figures 7 and 8.

Attention is directed to the fact that when the portable load carrying platforms H are in the slips 1 of the stationary depot they form substantially continuations of the platform 6 so that loading and unloading of the portable platforms is readily accomplished.

The specific manner in which the portable platforms are supported in the slips 1 forms no part of the present invention and the structure shown able centering means should be employed to accommodate variations in the lateral position of the truck in the slip, although this position is fairly accurately assured by guideways l1 formed in the floor of the slip.

The portable platforms are preferably equipped with hinged catwalks l8 on the sides thereof whichmay be swung from vertical positions to horizontal positions. For loading and unloading the latter position is employed and for transportation the catwalks are preferably upright. These catwalks are particularly advantageous during the transfer of cargo and freight to and from the platforms when elevated as shown in Figure '7 and for the same purpose the roller ramps H are equipped with similar catwalks IS.

The portable slips are preferably fabricated from structural steel to assure lightness without sacrificing strength. In plan view they are U- shaped and have arms or sides connected by a head or end portion 2!. The size of the portable slips is substantially the same as the fixed slips so that the truck or prime mover may back into them; and they are also of substantially the same height as the fixed slips so as to enable the removable load carrying platforms to be deposited thereon in the same way as the platforms are deposited in the permanent slips.

It is, of course, to be understood that the same recessed construction shown in Figure 9 may be employed in the portable slips, but for simplicity the portable slips have been illustrated as having the platforms rest right on top of the slips as shown in Figure 11.

It is also to be understood that when the truck carryina a load backs into a slip, either permanent or portable, the load must be elevated to have the platform clear the slip.

The arms or sides 20 of the portable slips are 4 hollow to provide pockets in which retractible wheels 22 are located. These wheels are mounted in forks 28 pivoted as at 24 to the structure of the slip so that upon swinging of the forks from a inclined position shown in Figures'3 and 10 to an upright position shown in Figures 4 and 5 the wheels 22 are projected from the bottom of the tached centrally to the yoke-like draw bar for connection to a complementary coupling member on the chassis of the prime mover. The forward end portion of the yoke-like draw bar is supported by a link 21 which permits the draw bar to swing forwardly. I

With the automatic hitch coupled as shown in Figure 3 the wheel carrying forks 23 are connected with the chassis of the truck or prime mover, and inasmuch as the elevatable frame swings in a rearward arc during elevation thereof, it follows that if elevated it will collide with the adjacent front end of the slip as shown in Figure 4.

In consequence to the application of such rearward force on the slip, the slip is virtually pushed rearwardly while its wheels are held against rearward movement until the wheel forks are swung to their upright positions shown in Figures 4 a same in place. Thereupon the elevatable frame of the truck or prime mover is lowered, which provides clearance between the prime mover and the slip so that the slip may be towed as a trailer.

To set the slip down on the ground upon reaching its desired location, the elevatable frame of the truck is again raised and the reverse procedure takes place.

Skids 30 at the four corners of the slip provide the ground engaging portions thereof and enable the same to be slid or pushed short distances.

In Figures 12 to 16, a somewhat modified construction for the slip is illustrated. In this case the top of the slip is covered with deck plates 3| and the inner edges of its side arms are cut away as at 82 for the admission of downwardly pro- Jecting centering guides 33 on the portable platforms (see Figure 14). Y

Adjacent to each of these cut away portions 32, guides 34 rise up from the deck of the slip to coact with the centering guides 38 in centering the platform as it is lowered onto the slip.

The ,latch mechanism by which the wheels are retained in operative ground engaging positions is illustrated in greater detail, particularly in Figure 15. As here shown, this latch comprises a pair of latchbars 35 pivoted to the structure of the slip as at 38 and each straddling the adjacent links 3'! which connect the wheel forks 38 with the transverse tow bar 39 and the link 40 by which the tow bar structure is supported. The latching action is obtained by the engagement of notches H in the latch bars with pins 42 on the connections between the links 40 and 81.

The latch bars 35 have tension springs 43 connected thereto to bias the sameto inoperative positions when the springs are tensioned. For tensioning the springs crank arms 44 are provided. These arms are adapted to be manually swung from a position shown in full lines in Figure 12 at which the springs are relaxed to an operative spring tensioning position shown in dotted 1 lines, the latter position being defined by stops ll engageable with the hubs 46 of levers 40.

It is also possible, as diagrammatically illustrated in Figure 16, and particularly with the slip construction just described, to manually bring the wheels into o erative round engag ng positions. This may be done by manually lifting the open end of the slip to rock the same on its forward skids until the wheels assume the positions at which the latch automatically secures them. Thereafter, by virture of the fact that the slip is substantially balanced over the wheels, it is a simple matter to lower the open end of the slip to substantially level position.

During elevation of th load, when mounted on the prime mover and especially in raising it to the height of the doorsill of the airplane, it is desirable that an operator located on the platform control the elevation of the load. For this purpose a control gear 41 is provided. This control gear is mounted at a convenient height above the elevatable frame to be readily accessible to an operator on the platform and is connected with the mechanism controlled thereby through telescoping control rods 48 Besides carrying cargo and freight, the portable platforms may provide the basis of a wide varlety of equipment which it is desirable to haul from place to place, as for instance a crane'l9 (see Figure 2) which has a wide variety of uses on an airport and for some types of freight may be used to load and unload the airplane.

It is, of course, understood that when the portable platforms are on the prime mover they are detachably locked in place to preclude the possibility of shifting under stress.

Cooperating centering means are also provided on the portable platforms and the prime mover. The specific nature of these centering means may be modified to suit design requirements, but in all cases cooperating guides on the portable platforms, the elevatable frame of the prime mover and the slips (both portable and stationary) should be incorporated to accommodate inevitable lateral misalignment.

In addition to the centering guides shown in Figures 9 and 14, a construction like that illustrated in Figure 1'7 is suitable. The construction there shown is similar to that of Figure 14 except that the guides 33 are equipped with rollers 33 to engage the inclined sides of the guides 34 on the slips and similar guides H! on the elevatable frame of the prime mover. If desired the roller carrying guide may be on the slips and on the elevatable frame of the prime mover instead of on the portable platform as shown, or where desirable one arrangement may be used at the front end while the other is used at the back end.

From the foregoing description, taken in connection with the accompanying drawings, it will be readily apparent to those skilled in the art. that this invention provides a system of handling air cargo and freight which is particularly well adapted for the loading and unloading of airplanes where the actual place of loading and unloading cannot be fixed and often must be located in remote parts of a landing field.

What I claim as my invention is:

1. In an airborne cargo and freight handling system for loading and unloading airplanes having doorsill heights varying between wide limits: the combination of a prime mover having a load supporting frame elevatable in a horizontal position to a height equal to that of the highest airplane doorsill; load carrying platforms adapted to be moved from place to place by the prime mover upon being picked up by its elevatable frame and to be eleveted to the doorsill height of an airplane to facilitate the transfer of cargo and freight between the airplane and the portable load carrying platform, said platforms having sufficient area to enable arrangement and rearrangement of the load thereon to facilitate loading and unloading of an airplane; and a portable unitary substantially U-shaped slip adapted to be towed from place to place by the prime mover, said portable slip being of a size to enable the prime mover to back into it while its load is elevated and of a height to assume support of the load carrying platform as its load supporting frame is lowered.

2. In a freight handling system of the charac ter described: a prime mover having an elevatable load carrying frame; a trailer having retractible wheels; means for coupling the trailer to the prime mover; and means motivated by the elevation of the elevatable frame of the prime mover for effecting relative movement between the trailer body and its wheels to bring the wheels into operative position supporting the trailer for transportation.

3. In combination: a prime mover having an elevatable load supporting frame; a structure adapted to be towed by the prime mover; retractible wheels for said structure; means for coupling said structure to the prime mover; and means operable by the hoisting of the elevatable load supporting frame of the prime mover for effecting relative movement between said structure and its wheels to bring the wheels into operative position supporting the structure for transportation.

4. In combination: a prime mover having an elevatable load supporting frame; a structure adapted to be towed by the prime mover; re-

tractible wheels for said structure; means pivoted to the structure and connected to the wheels so that swinging movement of said pivoted means effects projection and retraction of the wheels with respect to the structure; means for connecting said pivoted means with the chassis of the prime mover; and means for translating elevation of the elevatable load carrying frame of the prime mover into movement of said structure with respect to said pivoted means to lift the structure off the ground while its wheels remain engaged with the ground.

5. In combination: a prime mover having an elevatable load carrying frame which swings in a rearwardly projected arc as it is elevated; a structure adapted to be towed from place to place by the prime mover; retractible wheels for said structure; pivoted supporting members connecting the wheels with the structure so that pivotal movement of said members with respect to the structure raises the structure off the ground and supports the same on the wheels; means for connecting said pivoted members with the chassis of the prime mover; and means on said structure engageable by the rear of the elevatable load carrying frame of the prime mover as it swings rear wardly during elevation whereby the necessary pivotal movement of said pivoted members with respect to the structure to lift the same onto its wheels for portability is effected.

6. In combination: a prime mover having an elevatable load carrying frame which swings in a rearwardly projected are as it is elevated; a structure adapted to be towed from place to place by the prime mover; retractible wheels for said structure; pivoted supporting members connecting the wheels with the structure so that pivotal movement of said members with respect to the structure raises the structure off the ground and supports the same on the wheels; means for connecting said pivoted members with t e chassis of the prime mover; means on said structure engageable by the rear of the elevatable load carrying frame of the prime mover as it swings rearwardly during elevation whereby the necessary pivotal movement of said pivoted members with respect to the structure to lift the same onto its wheels for portability is effected; and latch means automatically operable to releasably hold the pivoted members in proper position to support the structure on its wheels.

'7. A portable slip for freight handling systerns comprising: a substantially U-shaped structure of a size to enable a truck to back into the space between the arms of the U and of a height to assume support of a removable platform carried by the truck as its elevatable load carrying frame descends While the truck is in the slip; supporting wheels for the slip one in each arm of the U; wheel arms pivoted to the structure of the slip and connected to the axles of the wheels so that pivotal movement of-the wheel arms in one direction projects the wheels from the underside of the slip to lift the slip off the ground, while swinging movement of the arms in the opposite' direction lowers the slip ontothe ground; and a releasable latch mechanism forholding the wheel arms in a position at which with the'pivoted wheel arms so that a forward pull-on the tow bar in the direction to tow the slip forwardly resisted by a force acting rearwardly on the slip projects the wheels from beneath the=slip and lifts the slip off the ground, said bar also providing means for towing the slip after its wheels are in supporting position; a releasable latch for holding the wheel arms in their wheel projecting positions; a biasing spring acting on the latch and tending to release t e same; and means for controlling the spring.

11. A portable slip for use in cargo and freight handling systems of the character described comprising: asubstantiallyU-shaped structure ada ted to restilatwise on the ground and. to s1 i p-' port a removable load carrying platform deposited on its arms by descent of the elevatable carrying frame of a truck on which the platform is removably mounted, said arms of the U -shaped so that downward swinging movement of the sides or arms of which are hollow and provide wheel pockets; wheels in said pockets; pivoted wheel arms for connecting the wheels to the structure of the slip whereby pivotal movement.

of said wheel arms in one direction projects the wheels from beneath the slip to lift the slip off the ground, while piovtal movement of the comprising: a substantially U-shaped structure,

the sides or arms of which are hollow and provide wheel pockets; wheels in said pockets; pivoted wheel arms for connecting the wheels to the structure of the slip wherebypivotal movement of said wheel arms in one direction projects the wheels from beneath the slip to lift the slip off the ground, while pivotal movement of the wheel arms in the opposite direction allows the slip to descend onto the ground; a tow bar connected with the pivoted wheel arms so that a forward pull on the tow bar in the direction to tow the slip forwardly resisted by a force acting rear wardly on the slip projects the wheels from beneath the slip and lifts the slip off the ground, said bar also providing means for towing the slip after its wheels are in supporting position; and

a releasable latch for holding the wheel arms in their wheel projecting positions.

10. A portable slip for use in cargo and freight handling systems of the character-described comprising: a substantially U-shaped structure, the

sides or arms of which are hollow and provide wheel pockets; wheels in said pockets; pivoted wheel arms for connecting the wheels to thee structure of the slip whereby pivotal movement of said wheel arms in one direction projects the wheels from beneath the slip to lift the slip'ofi the ground, while pivotal movement of the wheel,

arms in the opposite direction allows the slip to descend onto the ground; a tow bar connected slip forwardly accompanied by an opposing force forks projects the wheels from beneath the slip and vice versa; a-bail-like tow bar attached to the forks and so extended therefrom that a forward. pull on said bar in the direction to tow the ,acting on the slip projects the wheels' and ravity actuated latch mechanism for holding the tow bar in'its outwardly pulled position, 12. A portable slip for use in cargo and freight handling systems of the character described comprising: .a substantially U-shaped structure adapted to rest flatwise on the ground andto depositing preloaded portable platforms on support a removable load carrying latform posited on its arms by descent of the elevata l i le carrying frame of a truck on which the platform is removably mounted, said arms of the U-shaped slip being hollow to provide wheel pockets; supporting wheels in the pockets; forks embracing the wheels and mounting their axles; means prvotally mounting the forks in the arms of the slip so that downward swinging movement of the forks projects the wheels from beneath the slip and vice versa; a bail-like tow bar attached to the forks and so extended therefrom that a pull on said bar accompanied by an opposing force acting on the slip projects the wheels gravity actuated latch mechanism fOr holding the tow bar in its outwardly pulled position; and a link pivotally supported from the structure of the slip and supporting the freejend of the bailiiilgg tow bar adjacent to its latch engaging por- 13. The hereindescribed method of transferring airborne cargo and freight to and from an airplane, which comprises: moving portable slips on wh ch removable load carrying platforms may be deposited, onto an air field'close to any point to which an-airplane may be conveniently taxied;

e sl ps if airplane loading is to take place 'a r i d empty platforms if'airplane unloading is to take place; lifting a selected removable load carrying" platform'oif 'a slip andmoving it close to the H loading door of theai'rplane; elevating the selected. platform to the doorsill height ofv the air- "plane; and transferring cargo' and freight between-the airplane'and the platform, using'the platform for arranging the load as required.

14. The hereindescribed method of handling airborne cargo and freight at .an airplane depot; which comprises: moving one or more portable load supporting slips on which removable load carrying platform may be deposited onto an air field of the airplane depot close to any point or points to which airplanes can be conveniently taxied; transporting loaded platforms from a central loading station to, and depositing them on, portable slips located where airplane loading is to take place: depositing empty platforms on other slips where airplane unloading is to take place; picking up a selected platform from one of the portable slips and moving it into position adjacent to the loading door of an airplane; elevating the selected platform to the doorsill height of the airplane; bridging the gap between the elevated platform and the doorway of the airplane; and transferring cargo and freight between the airplane and the platform, using the platform for arranging the load as required.

15. The hereindescribed method of transferring airborne cargo and freight to and from an airplane, which comprises: moving a portable slip into which a truck may be moved and on which a removable load carrying platform may be deposited, onto an air field close to any point to which an airplane may be conveniently taxied; lifting a removable load carrying platform on,

the slip off the same by means of a hoist,truck moved into the slip under the platfonnf'moving the truck with the removable load carrying platform thereon close to the loading door of the airplane; elevating the platform to the doorsill height of the airplane by means of the hoist mechanism on the truck; bridging the gap between the elevated platform and the doorway of the airplane; and transferring cargo and freight between the airplane and the platform, using the platform for arran in the load as required.

16. The hereindescribed method of handling airborne cargo and freight at an airplane depot, which comprises: moving one or more portable load supporting slips into which a truck may be moved and on which removable load carrying platforms may be deposited, onto an air field of the airplane depot close to any point or points to which airplanes can be conveniently taxied; transporting loaded platforms from a central loading station equipped with stationary slips into which a truck may be moved, to. and depositing them on, portable slips located where airplane loading is to take place, by means of a truck having a horizontally elevatable frame adapted to pick a platform off a slip upon elevation and deposit a platform on a slip upon descent; depositing empty platforms on other portable'slips where airplane unloading is to take place, by means of the same or a similar truck; and picking up a platform from a portable slip and placing it in position adjacent to the loading door of an airplane with the platform elevated to the doorsill height of the airplane.

17. The hereindescribed method .of handling airborne cargo and freight at an airplane depot, which comprises: moving one or more portable load supporting slips into which a truck may be backed and on which removable load carrying platforms may be deposited, onto an air field of the airplane depot by means of a truck having an elevatable subframe, close to any point or points to which airplanes can be conveniently taxied: transporting loaded platforms by means of the truck from a central loading station equipped with stationary slips into which the truck may be backed, to, and depositing them on, portable slips located where airplane loading is to take place; depositing empty platforms on other portable slips where airplane unloading is to take place, by means of the truck; picking up a platform from a portable slip by means of the truck and moving it into position adjacent to the loading door of an airplane; and elevating the platform picked up by the truck by means ofits hoist mechanism to the doorsill height of the airplane.

GLENWAY MAXON, J l. 

